Object delete should probably check existence before close

[jeanconn]

I think the recursive runtime errors can occur because the __del__ method does not check to see if ftp is an attribute of self before trying to close it.

def __del__(self):
    """
    Delete object
    """
    self.ftp.close()

[jeanconn]

This filled up a bunch of the timelines/cmd_states log when lucky was down on Wednesday:

<<2016-Aug-24 10:13>> paramiko.ssh_exception.SSHException: Unable to connect to lucky: [Errno 110] Connection timed out
<<2016-Aug-24 10:13>> Closing remaining open files: /proj/sot/ska/data/cmd_states/cmd_states.h5... done
<<2016-Aug-24 10:13>> Exception RuntimeError: 'maximum recursion depth exceeded while calling a Python object' in <bound method SFTP.__del__ of <Ska.ftp.SFT
P object at 0x2b47d35f5310>> ignored
<<2016-Aug-24 10:13>> Exception RuntimeError: 'maximum recursion depth exceeded while calling a Python object' in <bound method SFTP.__del__ of <Ska.ftp.SFT
P object at 0x2b47d35f5310>> ignored
<<2016-Aug-24 10:13>> Exception RuntimeError: 'maximum recursion depth exceeded while calling a Python object' in <bound method SFTP.__del__ of <Ska.ftp.SFT
P object at 0x2b47d35f5310>> ignored
<<2016-Aug-24 10:13>> Exception RuntimeError: 'maximum recursion depth exceeded while calling a Python object' in <bound method SFTP.__del__ of <Ska.ftp.SFT
P object at 0x2b47d35f5310>> ignored

[taldcroft]

I guess putting that in a try block with except:pass would work.

[taldcroft]

Still having problems that might be related to this. I recently I have been getting fails on kadi because of Ska.ftp having a problem deleting the object at the end. Not sure where to go with this...

[jeanconn]

I had a plan to dig into #14 at some point, but, like our sqlite issue, I had a little trouble reliably creating the problem.

[jeanconn]

Probably worth noting in this issue that #12 was reverted.